Goal setting is an important component in successful teaching and learning, but relatively little is known about its impact on course persistence and achievement in massive open online courses. Using an experimental design and employing a variety of data including student writings, content-related assignment attempts, and quantitative achievement in the courses, we compared the outcomes of two groups of learners who were given different writing prompts at the beginning of their course. While no overall effects of writing prompt type on the dependent variables were observed, highly statistically significant differences were found when goal writings were more closely examined and compared via qualitative coding. When learners' written responses to prompts contained either learning or performance goals, those participants both achieved more and engaged in learning longer than participants whose written responses did not fall into either of these categories.